1. Field of the Invention
The present invention concerns a frame ground connecting device, for example a ground connection, for automation equipment such as a modular programmable automatic controller.
2. Description of the Prior Art
A programmable automatic controller includes one or more juxtaposed removable interface modules each containing, in a casing, processing electronics on one or more printed circuit cards which can be electrically connected to an interconnect printed circuit by respective connectors, the interconnect printed circuit being carried by a support and connecting the modules to each other and to a central processor unit. The housing can be fixed to the support and electrically connected to a conductive part of the latter by a frame ground connection device.
When the module is fixed to the support and connected to the interconnect bus it is preferable for a conductive part of the support and the module to be in mutual electrical contact to connect the printed circuits of the module to frame ground. When an operator mounts the module on the interconnect bus or demounts it, it is desirable for the frame ground connection to be made first or broken last, in order to protect the processor electronics.
This frame ground continuity of the module and the automatic controller and consequently grounding of the automatic controller, the conductive part of the support being connected to ground, are generally obtained by means of screws.
Another function of these screws is to fix the module to the support. Attaching a module by means of screws can take a relatively long time and requires the use of a tool.
For this reason the invention is directed to facilitating the mounting of the module on its support and to ensuring continuity of the frame ground connection during connection and disconnection of the circuits of the module and the interconnect printed circuit.
Consequently, the present invention concerns frame ground or ground connections for components of a module or connected to it.